A process for obtaining an image by imagewise exposure and subsequent uniform heating for development is called photothermography (light- and heat-sensitive image-forming process), and is characterized in that it enables one to obtain an image with ease by a dry process.
Among such processes, there is known a process of forming a visible image by thermal development using a photo-polymerizable composition and a heat-sensitive color-forming material as disclosed in JP-A-52-89915 (The term "JP-A" as used herein means an "unexamined published Japanese patent application"). This process comprises using a recording material in which two components of a two-component type heat-sensitive color-forming material are separately provided inside and outside, or on both sides, of the photo-polymerizing composition, and exposing and heating the recording material to set the exposed portion where no color is formed since the thermal components do not migrate, with the coloration reaction taking place in unexposed portion where the thermal components migrate to cause the coloration reaction, thereby forming an image.
As another process, there is known a process of using a recording material which comprises a photopolymerizable composition composed of a vinyl monomer having an acidic group and a photo-polymerization initiator and a dye precursor capable of forming a dye with the aid of an acid, as is disclosed in JP A 61 123838. This recording material is designed to provide a visible image by imagewise exposure and subsequent uniform heating in the vicinity of the above-described dye precursor thereby to react the dye precursor with the non-polymerized and diffused monomer having an acidic group.
These recording materials permit recording with either ultraviolet rays or visible light (e.g., visible light laser or LED) depending upon their design.
In a recording process using ultraviolet rays and those recording materials, either a transfer type recording material using two sheets or a monosheet type recording material (which does not require an additional sheet and is therefore more preferable) may be employed. However, a monosheet type recording materials capable of being recorded by visible light cannot be obtained.
This is true because recording by visible light requires a colored spectrally sensitizing agent for absorbing visible light and initiating photo-polymerization which remains in monosheet type recording materials and makes the resulting image indistinct.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a material capable of converting (i.e., developing) a polymer image obtained by photo hardened to a visible image by thermal processing, and an image-forming process using that material.
Another object of the present invention is to provide a recording material capable of responding to visible light and an image-forming process using that recording material.
A further object of the present invention is to provide a mono sheet type recording material requiring no unnecessary expendables.
These and other objects of the present invention will become apparent from the following description.
The above-described and other objects of the present invention are attained by a light- and heat-sensitive composition containing (a) a photo-hardenable composition and (b) a dye capable of losing its color upon being heated, a recording material containing that light- and heat-sensitive composition, and an image-forming process using that recording material.